Abstract P3018: SCARNA20 Promotes M2 Macrophage Polarization Under Endotoxemia And Reduces Inflammation

Abstract

Background: Macrophage polarization plays a key role in the inflammatory process. M1 pro-inflammatory and M2 anti-inflammatory phenotypes can down-regulate each other and may contribute to the pathogenesis of various diseases. Small Cajal Body Associated RNAs (SCARNAs) play a key role in alternative splicing and maturation of mRNAs. Our recent studies found that a combination of Procainamide (P, DNMT1 inhibitor) and Tubastatin A (T, HDAC6 inhibitor) reduces inflammation upon lipopolysaccharide (LPS) stimuli. Hypothesis: We hypothesize that the P+T treatment increases the expression of SCARNA20 hence reducing the proinflammatory response and promoting M2 macrophage polarization after LPS challenge. Methods and Results: To elucidate SCARNAs of interest during the inflammatory response, we treated macrophages with LPS (1μg/mL) and P (400nM/mL) + T (2.5μM/mL) for 1hr and performed RNA sequencing. Based on the sequencing results and qRT-PCR validation, SCARNA20 was the most significantly differentially expressed SCARNA between conditions (Fig. A) . The expression of TNFα was significantly reduced with the P+T treatment (Fig. B) . SCARNA20 overexpression (OE) showed an increase in the expression of the M2 marker CD163 and a reduction in the expression of the M1 marker CD80 (Fig. C) . Additionally, TNFα expression was significantly reduced in the SCARNA20 OE samples after the LPS challenge without treatment with P+T (Fig. D) . Finally, SCARNA20 knockdown macrophages (Fig. E) treated with P+T did not suppress TNFα expression (Fig. F) . Conclusions: We report for the first time that SCARNA20 is an important regulator of M2 macrophage polarization and pro-inflammatory response.